Plizzz pomagitex2-2xy-y2=1    x+y=2

[latex] \left \{ {{x^2-2xy-y^2=1} \atop {x+y=2}} \right. \\ \\ \left \{ {{(x-y)^2-2y^2=1} \atop {x+y=2}} \right\\ \\ \left \{ {{ (x-y-\sqrt{2}y)(x-y+\sqrt{2}y)=1} \atop {x+y=2}} \right. .\\ \\ \left \{ {{(2-2y-\sqrt{2}y)(2-2y+\sqrt{2}y)=1} \atop {x=2-y}} \right.\\ \\ y_{1}=\frac{\sqrt{5}+\sqrt{8}}{\sqrt{2}}\\ y_{2}=-\frac{\sqrt{5}-\sqrt{8}}{\sqrt{2}}\\ x_{1}=\frac{\sqrt{5}}{\sqrt{2}}\\ x_{2}=-\frac{\sqrt{5}}{\sqrt{2}}\\[/latex]